The present invention relates to arrangement for sealing of terminal posts in the covers of lead-acid storage cells and applies more particularly but not exclusively to the case where the material of that cover has a certain rigidity rendering it likely to damage when sealing is effected.
There exist numerous devices intended for effecting the sealing of terminals of lead-acid storage cells and in his work on "Storage Batteries" G. W. Vinyl discloses various types thereof. Among these, some use a sealing compound poured in a groove provided for that purpose. Others rely on the compressing of a flexible gasket obtained by screwing of a nut, the gasket being compressed between the cover and the nut, or between the cover and a shoulder of the terminal post is drawn upwards by the screwing of the nut.
More recently -- and this applies more particularly to storage cells having small dimensions, sealing was obtained by cold flow of the material of the terminal itself, taking advantage of the malleable qualities of lead, or sometimes, of indium. That cold flow can be obtained by increasing of the diameter of the terminal by the insertion, in a bore provided at the centre of the terminal, of a part such as a screw or a rod which is at least partly conical, having a maximum diameter greater than the inside diameter of the bore. That part can also consist of an expandable rivet.
The material of the terminal is thus compressed against the cover. However, this compression provides good sealing only if the cover is made of a flexible material. If the material of the cover is rigid, besides the fact that the contact between the terminal and the cover is not really fluid-tight, the increase of the diameter of the terminal risks causing a cracking of the cover.
This invention aims at remedying these drawbacks.
It has, among its objects, a seal in the cover of a lead-acid storage cell for a lead terminal post provided with a shoulder on the portion situated inside the storage cell and a blind hole opening towards the outside, in which is arranged a part such as a screw or an expandable rivet whose head bears on the outer surface of the cover, a flexible gasket being situated between the cover and the shoulder of the terminal post, characterized in that the action of the said part compresses the flexible gasket between the shoulder and the cover without however the contingent expansion of the lead terminal under the action of the said part effecting any contact between the cover and the expanded portion.
In this way, sealing is obtained simply by the compression of the flexible gasket without having to resort to a threading and a bulky nut and without having to fear a compression of the material against the cover which could effect a cracking thereof since the expanded portion of the terminal post does not even come into contact with the cover. Sealing is obtained exclusively at the level of the flexible gasket which is compressed either by the shortening of the expandable rivet or by the action of the screw.